1. Field of the Invention
The present invention relates to an automatic assembling system for automatically assembling products comprising a plurality of parts, and more particularly relates to an automatic assembling system which is advantageous in that a pallet transfer frequency is reduced for transferring a pallet between assembling steps, space efficiency is excellent, control of the number of parts in a pallet is needless, the cycle time for pallet supply is reduced, and mixed production (production of different types of products in a flow production) and fluctuation of the production are accommodated flexibly.
2. Description of the Related Art
Japanese Patent Laid-Open No. Sho 64-40231 (1989) has proposed a system provided with one assembling robot and a plurality of hands and tools in which the robot exchanges hands and tools, and feeds parts to an assembling cell for assembling a plurality of types of parts. The structure of this equipment is described below.
In this system, a plurality of pallets which carry a plurality of parts individually for types of parts are contained in a stockpiler, and pallets are transferred one by one according to a place where a robot can pick up a part from the pallet. The assembling robot is provided with adaptable hands and tools, picks up a required number of parts from the pallet, and assembles them. After assembling, the pallet is returned to the stockpiler, and waits for the next request in the assembling cycle.
This operation is repeated for required types of parts, and a series of assembling cycles is thus completed.
When the number of parts on a pallet decreases after repeated assembling cycles, desired parts on a plurality of pallets temporarily stored in a buffer are fed to the stockpiler. An empty pallet is removed from the production system, which comprises equipment, from the stockpiler by an expulsion mechanism. A carrier, which is provided to move between a warehouse unit and the production system, feeds new pallets to the buffer and recovers empty pallets.
This system is superior to the method disclosed in Japanese Patent Laid-Open No. Sho 63-295128 (1988), which uses a kit pallet carrying a plurality of different types of parts thereon, in that a pallet is used as it was stocked in a warehouse unit. Generally, parts carried on pallets containing a plurality of one type of part are fed to the warehouse unit for an assembling system. In the kit pallet system, parts of a plurality of types must be transferred from individual pallets which are fed to the warehouse unit to kit pallets. This transfer requires considerable work as heavy as the assembling work, and requires considerable man-hours.
However, the above-mentioned Japanese Patent Laid-Open No. 64-40231 (1989) involves some problems as described below.